Antitoxin strategy may help target other pathogens

June 18, 2012
This is an illustration of heterodimer chain attaching to Botulinum molecule at various binding sites. Credit: Illustration courtesy Beth Mellor/TUFTS

Researchers have unveiled a novel strategy for neutralizing unwanted molecules and clearing them from the body.

The strategy employs chains of binding agents, like "beads on a string", which two sites on one or more pathogenic molecules to neutralize their activity and promote their clearance by the body's immune system. The low-cost, easy-to-replicate tool has demonstrated applications against several different toxins, from those found in to those used in , and may also prove effective in targeting other types of pathogens.

The research team, based at Tufts University's Cummings School of Veterinary Medicine, demonstrated the method's efficacy in preventing the symptoms of botulism, a rare but caused by neurotoxin (BoNT), considered one of the most dangerous bioterror threat agents. The findings were presented earlier this year in .

"Currently, antitoxins are difficult to produce and have a short , making them very expensive. This new approach provides a low-cost way to develop highly effective antitoxins," said senior author Charles B. Shoemaker, PhD, professor of at Tufts University's Cummings School of Veterinary Medicine.

"This method has the potential to target a number of pathogens – not only toxins such as BoNT, but viruses or inflammatory cytokines. It is an important platform through which to address other significant diseases," says co-author Saul Tzipori, BVSc., DSc, PhD, professor of biomedical sciences and director of the Division of Infectious Diseases at the Cummings School.

Shoemaker and team had earlier found that pools of small 'tagged' binding agents were highly effective in targeting toxins, neutralizing their function, and flagging them for removal via the body's immune system in the presence of an anti-tag monoclonal antibody.

In the newly published in vivo study, the researchers have advanced this approach by linking two BoNT-binding agents together and including two copies of the tag. The binding agents are small, stable proteins derived genetically from unusual antibodies produced by toxin-immune alpacas. The resulting molecule, called a 'double-tagged heterodimer,' binds to two separate sites on the . Binding of this single heterodimeric agent much more effectively neutralizes the toxin than the unlinked monomer binding agents used in the prior research. In addition, attaching two tags to each of the two linked agents leads to toxin decoration by up to four anti-tag monoclonal antibodies, which promotes rapid toxin clearance from the blood, the researchers found (see figure).

The double-tagged heterodimer antitoxin agent strategy was shown to be efficacious against two types of BoNT in the PLoS ONE report. The antitoxin agents were administered at the time of exposure, or shortly after. Treated mice did not show any symptoms of – including the lethal paralysis which characterizes the disease, even when exposed to high toxin doses. Thus, the benefits of complex antitoxins were equaled or bettered by administration of two easy-to-produce agents; a heterodimer binding agent and an anti-tag monoclonal antibody.

According to Shoemaker, a major advantage of this approach is that, unlike treatments that only neutralize toxins, this treatment both neutralizes toxins and ensures their rapid clearance from the body. "Agents that only neutralize their pathogenic target will eventually dissociate which will allow the pathogen to continue doing damage if it is not eliminated," he said.

The group has now successfully taken the research further by building longer strings of binding agents that target multiple toxins with a single molecule—for example, the two types of Shiga toxins that are produced by some E. coli found in contaminated foods or the two toxins produced by hospital-acquired C. difficile infections.

Explore further: Newly discovered cell mechanism uses amplified nitric oxide to fight C. diff

More information: Mukherjee J, Tremblay JM, Leysath CE, Ofori K, Baldwin K, et al. "A Novel Strategy for Development of Recombinant Antitoxin Therapeutics Tested in a Mouse Botulism Model." PLoS ONE 7(1): e29941. Published online January 6, 2012, doi: 10.1371/journal.pone.0029941

Related Stories

Newly discovered cell mechanism uses amplified nitric oxide to fight C. diff

August 21, 2011
Groundbreaking research encompassing Case Western Reserve University School of Medicine and University Hospitals Case Medical Center, has uncovered a natural defense mechanism that is capable of inactivating the toxin that ...

Recommended for you

Engineered protein treatment found to reduce obesity in mice, rats and primates

October 19, 2017
(Medical Xpress)—A team of researchers with pharmaceutical company Amgen Inc. report that an engineered version of a protein naturally found in the body caused test mice, rats and cynomolgus monkeys to lose weight. In their ...

New procedure enables cultivation of human brain sections in the petri dish

October 19, 2017
Researchers at the University of Tübingen have become the first to keep human brain tissue alive outside the body for several weeks. The researchers, headed by Dr. Niklas Schwarz, Dr. Henner Koch and Dr. Thomas Wuttke at ...

Cancer drug found to offer promising results in treating sepsis in test mice

October 19, 2017
(Medical Xpress)—A combined team of researchers from China and the U.S. has found that a drug commonly used to treat lung cancer in humans offers a degree of protection against sepsis in test mice. In their paper published ...

Tracing cell death pathway points to drug targets for brain damage, kidney injury, asthma

October 19, 2017
University of Pittsburgh scientists are unlocking the complexities of a recently discovered cell death process that plays a key role in health and disease, and new findings link their discovery to asthma, kidney injury and ...

Study reveals key molecular link in major cell growth pathway

October 19, 2017
A team of scientists led by Whitehead Institute has uncovered a surprising molecular link that connects how cells regulate growth with how they sense and make available the nutrients required for growth. Their work, which ...

Inflammation trains the skin to heal faster

October 18, 2017
Scars may fade, but the skin remembers. New research from The Rockefeller University reveals that wounds or other harmful, inflammation-provoking experiences impart long-lasting memories to stem cells residing in the skin, ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.